1. Field of the Invention
The present invention relates to a brake control apparatus provided with pressurization control means for driving a pump at a requested motor rotational speed that is based on a predetermined pressurization force to feed brake fluid to a wheel cylinder in the case that the pressurization force is imparted to a wheel cylinder disposed in each wheel of a vehicle to generate braking force; and for regulating the pressurization force by controlling the position of a pressure regulation valve disposed in a circulation channel for circulating a portion of the fed brake fluid. The present invention also relates to a motor rotational speed computation method used in such a brake control apparatus.
2. Description of the Related Art
In a conventional brake control apparatus, a master cylinder pressure is generated by a master cylinder on the basis of brake operational force, and brake fluid is fed to the wheel cylinder provided to each wheel on the basis of the master cylinder pressure to control the braking force of the vehicle. Disposed between the master cylinder and the wheel cylinder in such a brake control apparatus are a pump driven by a motor to further pressurize brake fluid that is at the master cylinder pressure, a circulation channel for circulating a portion of the brake fluid discharged from the pump, and a pressure regulation valve disposed in the circulation channel to regulate the pressure difference (differential pressure) between the upstream side and the downstream side of the pump. A brake control apparatus having such a configuration controls the pressure (wheel cylinder pressure) of brake fluid fed to the wheel cylinder by circulating a portion of the brake fluid discharged from the pump back to the pump without feeding it to the wheel cylinder to regulate the differential pressure (e.g., Patent Document 1).
In this configuration, the pump described above has a problem in terms of its configuration in that the outputted pressure leaks (“pump leakage”) when the wheel cylinder pressure is varied. Patent Document 2 listed below provides a technique for improving such a problem.
The vehicle propulsion apparatus described in Patent Document 2 is provided with a flow rate meter for measuring the flow rate discharged from the pump. The measured flow rate and the flow rate discharged from the pump obtained by computation are compared to compute the amount of leakage, and control is carried out so as to compensate for the amount of leakage.    [Patent Document 1] JP (Kokai) 2001-71755    [Patent Document 2] JP (Kokai) 2000-158977